Upgrade from a Cary SLI-80 integrated amp

Re 5AR4 vs. 5U4: are they electrically similar?

The 5AR4 are indirectly heated and provide a smooth (slower ramp of current) start up of the amp. I have also been told that they present a lower impedance to the power supply and therefore provide better dynamics. I use them and felt they improved the transparency of the amp. I was also told that there is no need to spend big dollars here on NOS tubes, but to each his own, instead go with a pair of the lesser cost current production manufacturers. Certainly worth a try IMO.

Chuck

And I agree with the above poster that NOS tubes make a noticeable improvement.

Chuck

I am now listening to it with EI 6CA7 tubes; sounds interesting - very detailed and focused, but with small soundstage, the sound is inside the speakers (currently Silverline Sonata-III). Will try to install vintage GEC KT88 and play with speaker cables.

I am using NOS TS 6550s in my SLI-80 F1. Are KT88s preferable?

My current tubes, all NOS, are 4 TS 6550s, 2 RCA 6SN7/VT231 gray glass, 2 Mullard GZ34s and 2 Amperex 6992s.

I would like to get a bit more bass out of the amp given that I am using it with a pair of Nola Boxers. Any suggestions?